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November 24, 2009 Tuesday 3:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
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Aleks Diamond-Stanic
University of Arizona
The Growth of Supermassive Black Holes: A Biased View
The growth of supermassive black holes can be traced via the observed
luminosities of active galactic nuclei, but for most sources the line
of sight is blocked by gas and dust. Commonly used luminosity
indicators (e.g., X-ray continuum, optical line emission) are often
attenuated by several orders of magnitude, and it is difficult to
accurately estimate extinction corrections. The [O IV] 26 micron line
is more robust because it probes high-ionization gas and suffers
little dust attenuation. Using Spitzer measurements of [O IV] for a
complete sample of 90 local Seyfert galaxies, we find that the
luminosity distributions of obscured and unobscured AGNs are
indistinguishable, even though the obscured sources are systematically
fainter in terms of [O III] optical and 2-10 keV X-ray emission. In
addition, as part of of our work to calibrate the relationship between
[O IV] and AGN intrinsic luminosity, we find that even hard (10-200
keV) X-rays are biased tracers, particularly for Compton-thick
sources. This has important implications for the census of black hole
growth from future X-ray surveys.
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December 2, 2009 Wednesday 2:00 PM
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars
(hep)
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Shlomo Razamat
SUNY, Stony Brook
TBA
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December 2, 2009 Wednesday 4:00 PM
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars
(csmr)
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Hartmut Loewen
Heinrich-Heine-Universitat at Dusseldorf
Particle-resolved Instabilities in Colloidal Dispersions
Dispersions of colloidal particles are excellent
model systems of classical statistical mechanics in order to understand
the principles of self-organization processes.
Using an external field (e.g. electric
or magnetic field) the effective interaction between the colloidal
particles can be tailored and the system can be brought into
non-equilibrium in a controlled way. In this talk,
we shall discuss lane and band formation in oppositely
driven colloidal mixtures,
both in DC and AC driving fields. The experimental realization in colloids
and dusty plasmas is highlighted.
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December 3, 2009 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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James Carpenter
TBA
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December 4, 2009 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
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David Law
UCLA
Tidal Disruption in a Triaxial Milky Way Dark Matter Halo: A Revised Model for the Sgr dSph Galaxy
Observations of the lengthy stellar streams produced by the tidal destruction of the Sagittarius dwarf spheroidal galaxy (Sgr dSph) can provide strong constraints on the distribution of mass within the Milky Way. However, previous work has yielded conflicting results: while the angular precession of the streams has been thought to indicate an oblate shape for the Galactic halo, the radial velocities of stars in these streams are only reproduced in prolate halo models. I demonstrate that both observational characteristics are naturally reproduced by orbits within a triaxial Milky Way dark matter halo similar to that expected from current CDM theory. I conclude by summarizing the properties of the revised Milky Way --- Sgr system and discuss the possibility of using the Sgr stream to constrain the dark sector equivalence principle.
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December 9, 2009 Wednesday 2:00 PM
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars
(hep)
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Erick Weinberg
Columbia University
TBA
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December 10, 2009 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Sal Torquato
Princeton University
From Unusual Ground States to Packing Problems
Ground-state problems naturally arise in many fields, including physics, biology, materials science, and mathematics. A classical ground-state configuration of a system of interacting particles is one that minimizes the system potential energy. In the laboratory, for example, such states can be produced by slowly cooling a liquid to a temperature of absolute zero, and usually the ground states are close-packed crystal structures. I will describe isotropic interactions with unusual crystal ground states in three dimensions (e.g., diamond lattice) as well as disordered ground states, a counterintuitive phenomenon. I then will discuss the problem of determining the densest packings of particles in Euclidean spaces, which are closely related to ground-state problems. We provide the putative exponential improvement on Minkowski's 100-year-old lower bound on the maximal packing density of spheres in high dimensions. This suggests that disordered (rather than ordered) sphere packings may be the densest for sufficiently large dimension, implying the existence of disordered ground states for some continuous potentials. Finally, I will describe a recent Kepler-like conjecture for the maximal-density packings of a majority of the Platonic and Archimedean solids.
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December 11, 2009 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
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Jennifer Siegal-Gaskins
Ohio State
Using anisotropy to identify a dark matter signal in diffuse gamma-ray emission with Fermi
Dark matter annihilation in Galactic substructure will produce diffuse gamma-ray emission of remarkably constant intensity across the sky, making it difficult to disentangle this Galactic dark matter signal from the extragalactic gamma-ray background. Recent studies have considered the angular power spectrum of the diffuse emission from various extragalactic source classes and from Galactic dark matter. I'll discuss these results and show how the energy dependence of anisotropies in the total measured diffuse emission could be used to confidently identify a signal from dark matter in Fermi data. Finally, I'll present new results demonstrating that anisotropy analysis could significantly extend the sensitivity of current indirect dark matter searches.
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December 15, 2009 Tuesday 2:00 PM
Meyer 6th Floor SCM Area
Other Physics Department Events
(other)
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Physics Department Holiday Reception
RSVP to Lorelei DeMesa at 212-998-7711 or lorelei.demesa@nyu.edu
if you will be attending.
Light refreshments will be served.
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December 16, 2009 Wednesday 2:00 PM
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars
(hep)
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Christopher Herzog
Princeton University
TBA
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January 22, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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January 27, 2010 Wednesday 2:00 PM
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars
(hep)
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Gavin Salam
TBA
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January 29, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
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Vincent Desjacques
Institute for Theoretical Physics, Zurich
TBA
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February 4, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Matias Zaldarriaga
IAS
TBA
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February 5, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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February 12, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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February 19, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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February 24, 2010 Wednesday 2:00 PM
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars
(hep)
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Alexander Turbiner
UNAM, Mexico
TBA
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February 25, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Jerry Gollub
Haverford College
TBA
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February 26, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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March 4, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Adam Burrows
Princeton University
TBA
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March 5, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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March 11, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Janet Conrad
MIT
TBA
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March 12, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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March 26, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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April 1, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Jennifer Lewis
University of Illinois at Urbana-Champaign
TBA
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April 2, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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April 7, 2010 Wednesday 2:00 PM
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars
(hep)
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Samson Shatashvili
Trinity College Dublin
TBA
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April 8, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Meg Urry
Yale University
TBA
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April 9, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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April 16, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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April 22, 2010 Thursday 4:00 PM
Meyer 122
Physics Colloquia
(colloquia)
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Alex Filippenko
UC Berkeley
TBA
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April 23, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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April 30, 2010 Friday 2:30 PM
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars
(astro)
-
TBD TBD
TBD
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May 11, 2010 Tuesday 3:00 PM
TBD
Other Physics Department Events
(other)
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Physics Department Graduation Party
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